Mine is a wood furnice. When I bought the house, it was the major source of heat. Circulates air around the fire box, then into the air vents (conventional hot air system). Far better controlled and capable than a wood stove, but yes, would cost $Texas to put in if you don't already have forced hot air.

I actually sold our other 2 wood stoves because they're just silly compared to the furnice. I can burn wood, coal, oil, churches, very small rocks and salespeople in RMIC in it.

I live in the woods and forest manage my property, so have a pretty endless supply of wood and ways to get the wood to the house any time of year.